This relates generally to displays, and, more particularly, to variable refresh rate displays.
Electronic devices often include displays. Display driver circuitry is used to apply control signals to an array of pixels in a display. The array of pixels is used to display images for a user. In a liquid crystal display, for example, each pixel includes an electrode for applying a controllable electric field to a pixel-sized region of liquid crystal material. A thin-film transistor in each pixel is used to pass a data signal to the pixel from a data line in the display. There is a capacitance associated with the pixel-sized region of liquid crystal material and a storage capacitor is coupled in parallel with this capacitance to ensure that the pixel is able to store data signals between successive image frames.
The process of using the display driver circuitry to display images on the array of pixels in a display consumes power. Between frames, charge leaks out of each pixel. The capacitances in each pixel are refreshed each frame. Power is consumed in proportion to the refresh rate of the display as pixels are discharged and charged.
To help conserve power, some displays implement variable refresh rate schemes. When the display is being used normally, the display is refreshed at a high refresh rate. When it is desired to conserve power, the display is refreshed at a low refresh rate.
It can be challenging to implement a variable refresh rate scheme. If care is not taken, the display may exhibit undesirable visible artifacts such as transient flickering when transitioning between different refresh rates.
It would therefore be desirable to be able to provide improved techniques for controlling refresh rates in displays.